Stoker apparatus



J n, 14, 1941, w. R. MITTENDORF STOKER APPARATUS Filed May 29, 19:57 2 Sheets-Sheet l F IIIIIIIIIII!!! INVENTOR W\L\.\AM R. MH'TENDORF.

9146 ATTORN Jan. 14, 1941. MITTEND'OR'F 2,228,840

STQKER APPARATUS Filed May 29, 1937 2 Sheets-Sheet 2 INVENTOR WILL I'AM R. MlTTENDQRF.

BY ATTONY Patented Jan. 14, 1941 UNITED STATES PATENT OFFICE William R. Mittendorf, Cincinnati, Ohio, assignor to The E. B. Bardeo Range & Foundry Company, Cincinnati, Ohio, a corporation of Ohio Application May 29, 1931, Serial No. 145,610

' 9 Claims. (01. 110-4 This invention relates to stokingapparatus whereby coal, or other solid fuel, is transported from a source of fuel-supply, such as a hopper or bin, and delivered to the, retort or flrebowl of a furnace and therein subsequently distributed to the fire-bed.

Early forms of stoking devices heretofore used for this purpose, employed a cylindric ramor piston element for transporting the fuel from the hopper and discharging the same into the retort,

the said ram being reciprocably operated within a cylindric conduit, the receiving end of which had communicationwith the hopper and the delivery end withthe retort. This ram method 5 of feeding coal was decidedly advantageous in' respect to efficiency in that it accomplished the delivery to the retort of a largevolume of fuel in a short space of time and with the consumption of a comparatively small amount of power. Also in the case of underfed retorts, the ram method, giving intermittent delivery, was particularly desirable because the sudden push of the coal into the retort underneath the fire acted to disrupt the mass of burning fuel, leveling it off and closing up the large air holes therethrough. This is of great importance in the case of coking and caking coals which do not burn readily and which form large coke trees allowing free passage of air. However, there was a disadvantage attending this method due to the fact that the stroke of the ram was necessarily limited to a comparatively short movement and thus it was essential that the hopper be located close to the retort and at a distance somewhat less than the length of the ram stroke, or auxiliary feeding means be employed ,to carry the coal from a distant hopper to the ram chamber. Physical limitation precluded the use of the rain method of feeding coal in the vast majority of cases. Furthermore, as one of the objects of stocking apparatus is to accomplish the eilicient burning of thecheaper grades of coal, such as slack, the mm methodof feeding the coal to the hopper also had the serious disadvantage that it caused coherence or packing of the fuel particles of such grades of coal, particularly if the same was wet or even moist and this condition entailed'theemployment of agitating means .within the retort to disintegrate the coherent mass of fuel and effect distribution of the loosened fuel particles throughout the retort and delivery thereof to the fire-bed. Inthis matter, the reciprocating pusher-block type of agitator operating in the bottom of the retort in timed E relation with the ram impulses, has been generally employed, particularly in the case of long and narrow retorts.

In order to avoid the disadvantages of the ram method of delivering coal to theretort, later types of stoking devices employed a-rotating con- 5 veyor of the screw or spiral vane type disposed within a cylindric conduit extending from the hopper to the retort, the movement of the coal through the conduit resulting from the urge set up by the rotary movement of the spiral vane of 10 the conveyor. This enabled the hopper to be remotely spaced from the retort and substantially reduced the tendency of the coal to pack during transit but the low delivering efficiency of a rotating conveyor and its excessive waste of power 15 due, to unavoidable friction were serious disadvantages of this method. Also the delivery of coal bya rotating conveyor is substantially continuous and therefore there was no sudden impulse in the retort to disrupt the mass of burn- 2o ing fuel. In the early forms of such stokers, the conveyor screw was employed not only to trans port the coal from the hopper to the retort but the screw was arranged so as to extend a substantial distance into the retort, even the full 2 length thereof, in order that it may also function therein as a distributor element. This latter feature however had certain disadvantages of a particularly harmful nature-the distribution of the coal to the fire-bed was uneven, a pre- 30 ponderance of the fuel being delivered to that side of the retort toward which the screw rotated; also the section of the screw within the retort would deteriorate rapidly due to its proximity to the fire. Consequently, later designs of 85 stokers employing rotating conveyors are usually arranged with the conveyor terminating atthe entrance to the retort and a separate agitating and distributing device operating in the bottom of the retort. 7

Therefore, a principal object of this invention is to provide a stoker apparatus having the efliciency of the conventional ram method of delivery together with the advantages of the rotating conveyor and without the inherent 45 disadvantages of either.

Another obiect is to provide means for transporting coal from a hopper or bin to the retort by a method which is positive in delivery and definite as to volume.

Another object is to provide transporting means of this character which will effect delivery'of coal into the retort by a direct longitudinal thrust at intermittent time intervals. 4

Another object is to provide "means ofthis 68 the fuel particles to become packed during transit.

Another object is to provide means of this character which will permit locating the fuel hopper or bin at a substantially remote distance from the retort.

Another object is to provide a stoker apparatus comprising such transporting means in cooperative combination with agitating and distributing means within the retort.

Another object is to provide such a stokerapparatus which will be economical in operation in respect to power and fuel consumption, easy to manufacture at low cost and require a mini-' Fig. 1.

Fig. 3 is a sectional end elevation of the retort, taken on the line 2-2 of Fig. 2.

Fig. 4 is an undemeath'view of the intermittent gears forming part of the manipulating mechanism for the fuel transporting means:

Fig. 5 is a sectional elevation of sdid intermittent gears, taken on the line 55 of Fig. 4.

Fig. 6 is a side elevation of a modified form of manipulating mechanism for the fuel transporting means.

Fig. 7 is a. longitudinal plan view in section, taken on the line 1-1 of Fig. 6, and;

Fig. 8 is an end elevation, partly in section, taken on the line 2-8 of Fig. 6.

Referring to the drawings, Iii

generally a furnace having a retort comprising a trough portion l2 and tuyeres IS. A fuelsupply hopper or bin H may be located at any desired distance from the furnace and connected to the trough portion l2 of the retort II by means of a cylindric conduit 15' which may be constructed as a unitary element, as shown, or of as many sections as desired. In any case, the conduit I 5 is preferably united rigidly to the trough portion I2 at one end and similarly united to the hopper H at the other end, the said hopper having an opening it in the forward wall which coincides with the duct of the conduit l5. Thus the chamber within the hopper I4 is connected to the retort ll.

The forward bottom portion of the hopper I4 is formed internally with a semi-cylindric recess l1 having a rear wall ll, said recess being in axial alignment with theopening l6 andccnduit "l2. Disposed within the conduit l5 and extending into the recess I1 is a cylindric element l2 which may be termed "a retrohelically loaded ram and which, whe arranged and manipulated as hereinafter de cribed, serves to take fuel from the hopper l4, transport it through conduit i2 and positively thrust the fuel into the retort in definite volume at-intermittent time intervals.

The element It, which comprises a vane 22- formed as a helix around the axis of said element, is caused to move reciprocally forward toward the retort II and backward toward the hopper M. The forward movement of saidelement. is nonrotatory but. during the backward or return movement the element is given a rotary motion in such timed relation with its longitudinal movement and in such direction that the spiral vane 2,228,840 character which will minimize the tendency of will not change longitudinally from the path in which it moves.

The manipulation of the element I2 in this manner may be accomplished in various ways but I have herein shown, in Figs. 1, 2, 4 and 5, one form of operating mechanism which comprises a cylindric rack bar 2| suitably supported at one end for sliding and rotary movement in the wall ll of the hopper I4 and thereat having driving connection with the element 12, as by means of The rack bar 2| has a series of rack teeth 22 formed circumferentially thereof and said teeth are in operative engagement with a toothed pinion 24 which is journaled on a shaft 22 supported at each end in webs 22 extending from and below the hopper structure. A second rack bar 21 is slidably supported in brackets 22 and 22 also extending from the under side of the hopper structure and this second rack bar also has toothed engagement with the pinion 24 diametrically opposite that of the rack bar 2|.

Rotatably supported in a housing 22, which is preferably secured to a bracket 2| attached to a flanged extension 22 on the hopper i4, is a crankshaft 22 which may be driven in any suitable manner but I have herein provided a bevel gear 24 mounted on said crankshaft, within the housing 22, and drivingly connected thereto, the said gear meshing with a similar gear 25 secured to a drive shaft 26 forming part of a speed reducing device 21 which may be of any suitable character and attached to the housing 22 as shown.

Any form of power device, such as an electric motor 22, may be employed to operate-the said speed reducing device either directly or otherwise, as by means of pulleys 22 and 22 and belt 4|.

In order that reciprocatory movement may be imparted to the rack bar 21 and through it and pinion '22 impart similar movement to rack bar 2| and element I9 I prefer to operatlvely connect the said bar 21 to the crankshaft 22 by means of a link 22 pivotally connected at one end to crank arm oghead 42 of the crankshaft 22 by means of a stud 44 anchored in said head, the said link being similarly connected at its other end, by means of a stud 45, to member 42 attached to an extension 41 of the rack bar 21 and held in fixed longitudinal relation thereon by means of a collar 42 anchored to the said extension.

' Rotary movement may be imparted to the rack bar 2| and element |9,,on the backward or return stroke, in any suitable manner but -I have herein shown in Figs. 1, 2, 4 and 5 one form of operating mechanism which comprises a pair of intermittent bevel gears 42 and 52. Gear 42 is mounted upm and secured to shaft 22 and k formed as a sector having driving teeth 2| throughout less than half of .its circumference whereas the driven gear 22 is provided with teeth throughout its full circumference. As shown more clearly in Figs. 4 and 5, gear 42 is provided with a circular locking face 22 extending substantially degrees and disposed diametrically 1 opposite the teeth 2|; said locking face cooperates with another locking face attached to gear 22 and suitably spaced from the axis .of said gear so that gear 52 will be held against rotation whenever the teeth are out 'of engagement with teeth 1 22. Gear 52 may be supported in-any suitable manner but Ihave herein shown the same as being journaled at one "end in the wall of they housing 22 and at its other end in the bracket 2|. Therearend ofthecylindricrackbarfl 1:1

particularly those which are required to be long the webs 26. Secured to shaft 59 is a bevel gear slidably supported within the gear 50 and the gear means of a key 55 anchored in said gear anddisposed within a spline groove 56 in the rackbar 2 l For certain sizes and proportions of retorts,

and narrow in furnaces of large capacity, it is desirable to provide agitating and distributing means within the retort to cooperate with the fuel feeding means in getting proper distribution of the fuel throughout the extent of the retort. Such agitating and distributing means may be of any suitable character but I prefer to employ a reciprocating device, such as the well known pusher-block type of agitator, which may beprovided by extending the member 41 into the trough portion l2 of the retort H and mounting thereon one or more agitators or pusher-blocks 51 which may be anchored to the member 41 by any' suitable means such as bolts 58.

If desired, the rotary movement as required in the operation of element l9, may be accomplished directly by the reciprocatory movement of rack bar 21 by the driving mechanism shown in Figs. 6, '7 and 8 wherein the pinion 24 is drivingly secured to shaft 59 which is rotatably supported in 60 which meshes, with a similar gear 6! drivingly secured to a shaft 62 which is rotatably supported in extensions 63 and 64 of flanged extension 32 and bracket 3| respectively. Drivingly secured to shaft 62 is an internal clutch member 65 which,

- together with suitable rollers 66, roller thrust springs 61 and external clutch member 68, forms a one-way driving clutch whereby rotary motion may be transmitted to cylindric rack bar 21' si multaneously with its backward or return stroke. This may be accomplished by providing the external clutch member 68 with gear teeth 69 which mesh with the teeth of a gear mounted in the same manner and disposed in the same location as gear 50 and drivingly connected to the rack bar2l in the same way by means of key 55 disposed within groove 56 in the rack bar 21. If desired, a closure plate 1| may be provided to enclose the internal mechanism of the clutch. By means of this device, the element 19 will be subjected to rotary movement during its backward stroke only and-not during its forward stroke as the clutch is then inoperative.

While no means is herein shown for supplying and controlling draft air to the retort, nor for controlling the operation of the electric motor or other power device, it will be understood that any purposes.

In operation, coal is removed from the hopper or bin 14, transported through the conduit and thrust into the retort I-l solely by the manipulation-of the element l9 in the manner and through the means hereinbefore described. As the coal is being carried into the retort by the forward movement of the element 19, the agitators 51 are moving in relatively reverse direction. Owing to the fact that the delivery of coal into the retort is periodicthat is, periods of delivery (when element [9 moves toward the retort) alternating with periods of non-delivery (when said element is operating on its return stroke away from the retort)the feature of having the agitators 51 move in timed relation with an in reverse direction non-delivery periods, the coal in the retort is subjected solely to the distributive influence of agitators 51 as they move forward and conversely, during periods of delivery when element 19 pushes forwardly into the retort, the raking action of agitators 51 is in opposition thereto and this compound action serves to effectively break up caking. of the coal and thereby enables agi-' tators 51 to accomplish better distribution on their subsequent forward movement.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a stoker mechanism, in combination, a hopper for holding a supply of coal, a retort spaced from said hopper and having a receiving opening, a cylindric conduit extending from said hopper to said receiving opening, a cylindric ram freely disposedwithin said conduit and having a helically formed groove extending throughout its length, said ram having one end disposed in communicative relation with said hopper and its other end disposed in similar relation with said retort, means to cause relatively timed rotary and longitudinal movement of said ram toward said hopper and non-rotary longitudinal movement thereof toward said retort whereby coal may be caused to move from said hopper through the groove in said ram and be thrust into said retort, said means comprising a crank operated device, a pusher-block device disposed within said retort in a plane below said receiving opening and adapted to agitate and distribute the coal within the retort, and a member operatively connecting said pusher-blockdevice with said means so as to cause reciprocatory movement of said pusherblock device simultaneously with the longitudinal movement of said ram in timedrelation therewith and in reverse direction thereto.

2. In a stoker apparatus comprising a container for holding a supply of coal and a retort in which coal is to be burned, the combination of means for transporting coal from said container to said retort and a reciprocable device in said retort to agitate and distribute the coal therein, said means comprising a, cylindric conduit extending from said container to said retort, a cylindric ram movable reciprocally within said conduit and having a helically formed coalcarrying channel extending throughout the length thereof and means comprising a crankoperated device to manipulate said ram so as to cause a portionof the coal in said container to enter said channel at one end. and to subsequently cause said portion of coal to. move through said conduit and out of the other end of said channel into said retort and said reciprocable device being associated with said crankoperated device so as to be actuated thereby in timed relation with the reciprocal movement of said ram and in reversed direction thereto.

3. In a stoker apparatus, the combination member reciprocable longitudinally within said.

retort to distribute and agitate the coal therein, .and means operatively connecting said member with said crank-operated device so as to actuate said member in timed relation with the reciprocal movement of said element and in reverse direction thereto. I

4. In a stoker apparatus, the Combination with a hopper, a retort and a conduit extending from said hopper to said retort; of a coal-feeding element reciprocable longitudinally of said conduit, a rotating power device, means comprising gearing operatively connecting said power device to said element for imparting reciprocatory movement thereto, and other means comprising intermittent gearing associated with said power device and said element for rotating said element as it is being moved longitudinally in one direction.

5. In a stoker apparatus, the combination with a hopper, a retort and a conduit extending from said hopper to said retort; of a coal-feeding element slidabiy and rotatably supported and enclosed within said conduit, means to move said element endwise non-rotatively in one direction and endwise rotatively in the opposite direction, said means comprising rack-and-pinion gearing for accomplishing said endwise movements and intermittent gearing for accomplishing said rotative movement.

6. In a stoker apparatus, the combination with a hopper, a retort and a conduit extending from said hopper to said retort; oi a coal feeding element'slidabiy and rotatably supported and enclosed within said conduit, a crank-operated device for imparting longitudinally reciprocatory movement to said element, and means associated with said device for imparting rotary movement to said element during its endwise movement in one direction only, said means comprising a gear drivingiy oonnectedto said element.

7. In a stoker apparatus, the combination with a container .adapted to contain coal, a retort in which coal may be burned, and a conduit extending from said container to said retort: of a helically grooved cylindric ram for moving coal from the container through the conduit into the retort, a member in the retort adapted to distribute the coal throughout the retort area and to agitate the fire-bed, and means comprising a crank-operated device for imparting longitudinally reciprocatory movement to said ram and said member simultaneously and in reverse direction one with the other, and other means for I imparting rotary movement to said ram during its longitudinal movement in one direction only. 8. In a stoker apparatus, the combination with a container adapted to contain coal, a retort in which coal may be burned, and a conduit extending from said container to said retort; of a coal-feeding element slidably and rotatably supported within said conduit and adapted ior moving coal from the container through the conduit into the retort, means to move said element end- [wise non-rotatively in one direction and endwise rotatively in the opposite direction, said means comprising a revolving crank for accomplishing said endwise movements and gearing associated therewith for accomplishing said r0 tative movement.

9. In a stoker apparatus, the combination with a hopper, a retortand a conduit extending from said hopper to said retort; of a coal-feeding ele- -ment rotatably and slidably supported and enclosed within the conduit, a rotating power device, means operatively connecting said power device to said element to cause said element to bereciprocatedlongitudinaily of said conduit, said means comprising a revolving crank, and other means operatively connected to said element to cause saidelement to be rotated simultaneously with its longitudinal movement in one direction only, said othermeans comprising a gear adapted to be inoperative during the longitudinal movement oi said element in the opposite direction.

WILLIAM R. MII'IENDQRF. 

